Cosmic Ghost Rider was Frank Castle, who was killed in a battle alongside the other heroes of Earth against Thanos and was given a second chance to live again as the Ghost Rider by Mephisto upon hearing Castle's dying wish to punish Thanos. However, upon his return, Castle finds out that nearly everyone was killed by Thanos and finds him nowhere in sight until Galactus comes to Earth asking for help from the presumably deceased Mr. Fantastic to defeat Thanos. Castle then makes a deal with Galactus by letting him become Galactus' herald in exchange for his help.
Centuries afterwards, Castle and Galactus were finally able to confront Thanos in battle but Galactus is easily defeated and killed by Thanos and Castle begins a new partnership with Thanos when Thanos offers him the chance to punish evil even worse than him.
Castle is sent to the past by Thanos in order to find and capture his younger self, which was done by incapacitating Thanos with a fragment of the Time Gem and chains made out of the bones of Cyttorak before dragging him into the future. Castle used his Penance stare to show Thanos all the atrocities he has committed and the ones he will commit in the future. During the confrontation with Future King Thanos and The Fallen Surfer, Castle died again as Surfer smashed his head with Mjonir.
In death Castle was retrieved by Odin who rewarded him Valhalla due to being a noteworthy warrior. Castle rebelled in Valhalla as he doesn’t believe himself deserving of a noble death, so Odin offered to send him any place or time of his choice. Castle chooses Titan when Thanos was an infant so he can kill him before turning into a monster. Upon using his Penance Stare on baby Thanos, Frank realized he wasn't evil yet and decided to take him under his wing instead as to change his future. Frank approached Galactus to help raise Thanos as that was the only person he knew in this time period. After reading Frank’s mind Galactus decides it’s better to kill baby Thanos before he can Galactus is interrupted by The Watcher then an alternate universe Cable & Guardians of the Galaxy.
Cable informs Castle that Thanos became much worse under his care and summoned hundreds of alternate heroes in order to kill baby Thanos & Frank. Frank killed most of the heroes until he was knocked out, when he awaken he saw baby Thanos had killed the remaining ones except Cable. When Castle approached Cable, Cable was shot by a future Thanos wearing Punisher fatigues. Thanos took Castle into the future to show him the world they created; Castle raised Thanos to by an authoritarian dictator of Earth. Witnessing the horror he unleashed Castle killed Punisher Thanos and returned baby Thanos to his time, where he was greeted by Death. Who said Thanos adventure with Castle instilled to him the need for death and gave him the qualities suitable to be her avatar.
Due to being a Ghost Rider and a former Herald of Galactus Frank possess a unique combination of abilities.
- Immortality: Cosmic Ghost Rider lived missions of years without aging.
- Energy Projection: The Rider can fire devastating blasts of cosmic energy from his hands.
- Penance Stare: As a Spirit of Vegence Castle can make an individual feel every sin they have committed.
- Hellfire Manipulation